Groundwater Movement and Cavern Development
in the
Chester Series in Indiana1
Richard
L.
Powell, Indiana Geological Survey
The hills and valleys of the Crawford Upland of south-central
Indiana (Figure 1-A) are underlain by rocks of the West Baden and
Stephensport Groups (Chester Series) (Figure 1-B). These rocks typically consist of repeated sequences of dense jointed limestone underlain
by shale and overlain by thick jointed sandstone. Groundwater movement
is mostly within the sandstones and
limestones, for the shales are
relatively impermeable. Furthermore, groundwater movement seems to
be most active in a zone adjacent to the outcrop.
Evidence of ground water movement within the rocks of the West
Baden and Stephensport Groups is mostly in the form of springs along
the outcrop and solution features in the limestones. The most common
features noticeable along the outcrop of the limestones are
enlarged vertical joints. These are particularly prominent in shallow
road cuts and quarry exposures. The solution of limestone along
bedding planes is uncommon except at the base of the limestones, and
is secondary to solution along vertical joints.
Small solution channels
are common along the base of the limestones and some of these feed
small springs that are characteristic of the Crawford Upland. Larger
solution channels and caverns feed larger springs, usually situated in
spring alcoves, although many of the caverns cannot be entered because
their entrances are blocked by collapse of the rock faces above the
solution
springs.
Caves are abundant along the outcrop of the various West Baden
and Stephensport limestones (3). Most of the caves are small and
extend only a short distance from the outcrop to places where the
passage is blocked by collapse material or becomes too small to traverse.
McGrain and Bandy (1) described four short caverns in the Beech
Creek Limestone which are typical of most caverns in limestones of
the Chester Series. They stated that ground water from the overlying
sandstone supplies the water for cavern development by joint enlargement, and that modification by collapse is minor.
the
The areal extent of the outcrop of the relatively thin limestones of
West Baden and Stephensport Groups is very limited in comparison
the underlying thicker limestone of the Blue River Group which
crop out extensively on the Mitchell Plain to the east of the Crawford
Upland. Karst features, which are typical of the Mitchell Plain, exist
but are not common on the limestone surfaces of the Crawford Upland.
The lack of sinkholes and sinking streams on some limestone surfaces
of the Crawford Upland that are known to be underlain by well developed caverns indicates that these caves have been formed by some means
to
Published with permission of the State Geologist, Indiana Department of
1.
Natural Resources.
210
Geology and Geography
5
UJ
>
CO
CO
UJ
a.
ec
o
UJ
CO
o
211
LITHOLOGY
FORMATION
or
1
1
I
I
I
Glen Dean Ls.
1
1
cr
Hardinsburg Frn.
o
a.
CO
<
z
I
I
UJ
X
£L
UJ
1-
a
a.
UJ
CO
h-
I
Golconda Ls.
1
1
i
i
i
i
i
S8B
i
i
to
1
1
i
i
i
Beech Creek
UJ
X
o
to
Elwren Fm.
Ul
Q
<
m
-c
i
co
UJ
Reelsville Ls.
i
'.•'. '','.
T7?\.
"7
i
i
i
i
i
Sample Fm.
Beaver Bend
uj or
m^
i
i'
i
L
I_J
1
1
1
1
!
PacHi Ls.
1
1
!
Ste. Genevieve Ls.
Vertical scale
100 Feet
;
: :
:.
.
Ls.
Bethel Fm.
5
:r,-.-.-.-.i
Ls.
co
"•'•.
to
Big Clifty Fm.
B
:^--:
OS
^
—
" cavern • JLi
Figure
A.
Map
of Indiana
1
showing the location of the Crawford Upland and Hay Cave.
column showing' the rock types of the West Baden
B. Generalized stratigraphic
and Stephensport Groups.
diagram showing the relationships
C. Idealized block
to rock types.
of
groundwater movement
Indiana Academy of Science
212
other than by the type of subterranean stream piracy or stream diversion
that is characteristic of the Mitchell Plain.
Sinkholes have developed on locally extensive limestone surfaces in
the Crawford Upland, particularly on the thicker limestones. Most of
these are collapse sinkholes, which have developed over caverns where
the limestone has been removed from a larger area than the overlying
rocks can span without collapsing.
Caverns within the Chester limestones are nearly always situated
where the limestone is underlain by shale and overlain by permeable
sandstone. The outcrop of the limestone in the vicinity of many of the
caverns consists of a nearly vertical face beneath overhanging ledges
of sandstone. Thus the limestone has practically no areal extent on the
outcrop except where an occasional gully has been eroded through some
of
the
sandstone.
Groundwater within the sandstones and limestones of the West
Baden and Stephensport Groups is derived from direct infiltration of
precipitation plus some surface run-off from the hillside (Figure 1-C).
Run-off descending the slope above the sandstone cannot enter the
sandstone to become groundwater until it has passed over the lowest
overlying impermeable zone, generally a shale. Thus the zone of surface
water infiltration is closely related to the areal extent of the outcrop
of the sandstone. The water is not uniformly absorbed by the sandstone
because of local differences in permeability. Water entering a permeable
sandstone descends rapidly to the water table where it moves laterally
to a release point. Inasmuch as the standstones are commonly underlain by rocks of even less uniform permeability, groundwater in the
basal part of the sandstone constitutes a perched water body. If shale
underlies the sandstone the groundwater must flow laterally to a spring
at the outcrop or to where a more permeable lithology underlies the
sandstone. Where jointed limestone underlies the sandstone, descending
groundwater flows laterally on top of the limestone, then downward into
joints in the limestone. The volume, rate and direction of flow of water
from the sandstone depend upon the amount of water available and
the size and spacing of the openings along the joints at the upper
surface of the limestone.
The movement of water through the limestone depends upon the
character of the jointing. Two sets of joints are common, but systems
with three, four and five sets are known. The amount of open space
along these joints determines the rate and volume of water that may
enter the limestone. Many of the joints that can be viewed from within
a cave are tight and do not appear to be water bearing; others range
from shallow to deep and narrow to broad crevices. Joints are generally
more widely opened along the outcrop where mass wasting has caused
slight movement of the blocks of limestone.
Groundwater descending through
joints in the limestone differentially
The magnitude of solution
depends upon the acidity of the water, its amount and rate of flow, and
the solubility of the limestone with which it comes in contact. In
dissolves portions of the walls of the joints.
general, the greater the rate of flow, the greater the rate of solution;
Geology and Geography
therefore those joints which receive the greatest
those most likely to be further enlarged. Nearly
the limestones exhibit joint control (1).
213
amount
all
of water are
cave passages in
Shale most commonly underlies the limestones of the West Baden
and Stephensport Groups. Water descending through joints in the limestone is therefore forced to flow laterally along joints near the base of
the limestone, thus forming a second perched water body. Secondarily
enlarged bedding plane surfaces and horizontal solution scars are occasionally prominent in the otherwise joint controlled passages. Water is
released from the narrow vertical joints either into cavern passages
or to the outcrop. The caverns usually open onto the outcrop within a
spring alcove formed by erosion of the impermeable shale downstream
from the entrance of the cave, subsequently undermining the jointed
limestone, and causing mass wasting of the limestone and overlying
sandstone.
Ray Cave,
located at the type locality of the Beech Creek Limeshows the close relationship of a typical cavern to the outcrop.
The limestone here is 24.5 feet thick and is overlain by 37 feet of sandstone and 20 feet of shale and underlain by 46 feet of shale and sandstone (2). Ray Cave is developed down the dip of the strata, which is
to the west at about 45 feet per mile in the vicinity of the cave
stone,
(Figure 2-A).
Ray Cave is the longest known cave within limestones of the West
Baden and Stephensport Groups. It consists of passages that have been
mapped for a distance of about 9000 feet without
The cave contains a small stream for its entire
passage
is
large enough to permit walking, but
finding a terminus.
length.
many
The main
collapsed areas
require climbing and crawling over and through breakdown. There are
few side passages, but there are two in the downstream part of the
cave (Figure 2-B). One side passage near the entrance extends from
the cave stream level in the main passage to the top of the outcrop'of
the limestone, and another trends northward along the ridge. A third
opening to the surface extends through the sandstone at the first
collapsed area across the main passage.
Ray Cave closely follows the surface exposure of the Beech Creek
Limestone, rather than meandering at random beneath the ridge (Figure
2-A). The cave lies within 300 feet of the outcrop for most of its
mapped distance. The greatest known distance from an adjacent outcrop is about 700 feet, which is at a place where the cave passes beneath
a small spur north of the main ridge (north of Combs School). The
main ridge has an average width of about 3000 feet at the level of the
Beech Creek Limestone and is about 2000 feet wide at its narrowest
place, near the eastern or upstream end of the mapped cavern.
Ray Cave contains numerous domes ranging from 15 to 20 feet
high which extend upward from the ceiling of the cave passage, often
to the base of the overlying sandstone. In addition, there are several
high open joints. These vertical solution features indicate that water
has entered the cave from the top of the limestone, and most likely
from the overlying sandstone. The domes and high fissure passages are
located where Ray Cave is closest to the outcrop (Figure 2-B). Some
Indiana Academy of Science
214
Contour Interval 10 Feet
EXPLANATION
.;
f>
100
A. Topographic
crop of the
200
Outcrop area of sandstone
Dome
•^
Collapsed area
©
Ceiling height
300 Feet
map showing
Beech Creek
Figure
2
the location and extent of Ray Cave and the outLimestone. Base modified from the Solsberry
Quadrangle.
B.
Map
Cave
of the downstream portion of Ray Cave showing the relationship of the
to the outcrop of limestone and sandstone.
Geology and Geography
215
water enters the cave passage at the collapsed areas which are also veryThe collapsed material is mostly limestone but
contains some sandstone blocks and sandstone is exposed at the top of
several of the collapse areas. Collapse and vertical solution features
are not found where the cave lies more than a few hundred feet from
close to the outcrop (1).
the outcrop.
No sinkholes are known along the ridge above Ray Cave nor
adjacent to the outcrop of the Beech Creek Limestone. Thus, the stream
in Ray Cave is not fed by surface drainage as are the caves beneath
the Mitchell Plain. The flow regimen of Ray Cave is not similar to that
of a stormwater cavern. The stream in Ray Cave does not appear to
dry up completely, as do some stormwater caverns, nor does it appear
subject to flash flooding. The observed and inferred flood levels in
Ray Cave are low in comparison to those of stormwater caverns. Similar
observations have been made for most of the caves in limestones of the
West Baden and Stephensport Groups. The relatively uniform permeability in the sandstone and the storage capacity of its perched water
body may serve to regulate the flow of water in the caves in these
limestones.
summary, the features of the known caverns in all of the limeWest Baden and Stephensport Groups indicate the direction
and amount of groundwater movement within the caverns and the
overlying strata. The presence of high open joints and domes in these
caves is proof that groundwater has entered the cave from an overlying
permeable zone. The nearness of the caverns to the outcrop indicates
that there is a close relationship between amount of groundwater flow
and proximity to outcrop. The cavern passages tend to follow widened
joints down the dip of the strata. The flow characteristics of the springs
and caverns indicate that the flow is somewhat regulated, perhaps by
storage and release of water from an overlying perched water body
which is recharged by surface run-off and precipitation. Although
In
stones of the
the caves are not generally associated with surface karst features which
would indicate their presence, the collapse of the cave passage at points
near the outcrop creates surface openings for the direct infiltration of
small amounts of surface water.
Literature Cited
1.
McGrain, Preston, and Bandy, O. L. 1954. Origin and development of
caverns in the Beech Creek Limestone in Indiana. Natl. Speleol. Soc. Bull.
16,
p.
p.
65-70,
5
figs.;
(abs.)
Indiana Acad.
Sci.
Proc.
for
1954,
Vol.
64,
175, 1955.
2.
Malott,
3.
Powell, R.
C. A. 1952. Stratigraphy of the Ste. Genevieve and Chester formations of southern Indiana. Edwards Letter Shop, Ann Arbor, Mich., 105 pp.
127 pages, 4
L.
1961.
pis.,
5S
Caves of Indiana. Ind. Geol. Survey, Circular No.
figs.,
1
table.
S,